Flow elements for use with flexible spinal needles, needle assemblies and methods therefor

ABSTRACT

A flow element for use with flexible needles and flexible needle assemblies to minimize flow occlusion within a flexible needle is provided. The flow element is particularly suited for uses with a flexible needle for minimizing incidence of post-dural puncture headache. The flow element includes a body having an internal flow path for conducting a fluid through a flexible needle, and an anti-restriction member. The anti-restriction member includes an elongated body, a proximal end coupled to the body within the internal flow path, and a distal end for disposing at least a portion of the elongated body within a flexible needle. A flexible spinal needle assembly for minimizing flow occlusion through an internal flow path of a flexible needle by unintended kinking that is potentially caused by ligament or muscle layer movements is also provided. In other embodiments, a flexible spinal needle assembly, a flexible spinal needle assembly kit, a method for installing a flexible spinal needle assembly, and a process for producing a flow element are provided.

FIELD OF THE INVENTION

This invention relates generally to medical devices, and particularly tostructures for fluid occlusion prevention in medical needles. It isparticularly directed to a flow element for use with flexible needlesand flexible spinal needle assemblies, including methods therefor.

BACKGROUND

The advantages of continuous spinal anesthesia have long beenappreciated by anesthesiologists. Unlike conventional single-shottechniques, continuous spinal anesthesia (“CSA”) with an indwellingcatheter allows anesthesia of unlimited duration and the ability tocarefully control the level of the block by administering repeatedsmall, incremental doses of anesthetic. As compared to continuousepidural anesthesia, which has become widely used as a substitute forspinal, CSA generally requires far less drug to achieve the desiredeffect, has a definite endpoint of correct catheter placement, requiresno “test dose,” and produces a much more reliable, less spotty block.

Unfortunately, technical problems have severely limited the usefulnessof continuous spinal techniques. Until recently, the standard techniqueof inserting the spinal catheter through the spinal needle, coupled withthe difficulty of manufacturing truly small needles and catheters, hasmeant large needles and catheters were required, resulting in anunacceptably high incidence of post-dural puncture headaches (“PDPH”).

In the mid 1980's, various advances fueled renewed interest in spinalanesthesia in general and in CSA in particular. Improvements inmanufacturing ever-smaller conventional (QUINCKE.™) spinal needles of 25gauge, 26 gauge, and even 30 gauge significantly reduced PDPH incidence.These results allowed for the use of spinal anesthesia in age groups andprocedures not previously considered suitable.

At the same time, advances in catheter manufacture made possible spinalcatheters of 28 gauge and 322 gauge which would fit through relativelysmall spinal needles. Unfortunately, these catheters proved difficult tohandle, difficult to make, expensive, and, more ominously, associatedwith several reports of neurologic damage (i. e., cauda equinasyndrome). Many clinicians therefore tried and abandoned them, and theywere ultimately removed from the market by the Food and DrugAdministration (“FDA”).

The FDA's decision to recall and ban the marketing of microspinalcatheters for CSA in the U.S., and its requirement that any new devicefor CSA be subjected to an extremely stringent pre-market approvalprocess, has resulted in a freeze on the development of these products,at least in the United States. Nevertheless, the injection of localanesthetics for the establishment of surgical anesthesia is not the onlyuse to which such devices might beneficially be put. In fact, theinjection of narcotics, such as FENTANYL.™, for analgesia of labor wouldbe a very desirable use of such catheters.

Installing a conventional catheter generally requires various cumbersomesteps involving threading long, very thin catheters through a spinalneedle. Simply threading a catheter into the end of a spinal needle canbe so difficult that some manufacturers include a “threading aid” aspart of their kit. Once threaded, a degree of uncertainty exists for theclinician about how far to insert the catheter. Also, a risk exists thata piece of the catheter might be sheared off by the needle if thecatheter were to be pulled back during the threading operation. In suchcase, bits of catheter could potentially be left behind in theintrathecal space. Furthermore, removing the spinal needle while holdingthe catheter in position can be a challenge. Additionally, attaching ahub/injection adapter to the naked end of the 28 g or 32 g catheter canbe even more of a challenge. Finally, once the adapter is successfullyattached, the small lumen of the catheter permits only a slow flow ofeither CSF or anesthetic. In short, the conventional spinal catheterthreading operation requires considerable time and effort on the part ofa clinician.

A parallel technical development has been the introduction ofnon-cutting spinal needles, such as the “Pencil Point” type needles,which have been shown to drastically reduce PDPH incidence. Examples ofPencil Point type needles include the Sprotte and Whitacre non-cuttingspinal needles. In terms of PDPH incidence, a 22 gauge Sprotte seems tobe roughly equivalent to a 25 gauge or 26 gauge Quincke, while a 24gauge Sprotte or 25 gauge Whitacre essentially eliminates the risk ofPDPH.

One problem of Sprotte and Whitacre non-cutting spinal needles is thatthe injection orifice is on the side of the needle. Failures of spinalanesthesia have been described as when the needle was “half-in,half-out” of the intrathecal space. Another problem with Sprotte andWhitacre spinal needles is that the smooth curved tip profile providesno definitive feedback signal or “click” when the dura is punctured.Such lack of feedback contributes to uncertainty of catheter tipplacement.

One solution overcoming the limitations of the conventional cathetersmentioned above and approved by the FDA is a flexible spinal needledescribed in U.S. patent application Ser. No. 10/694,235, filed Oct. 27,2003, (U.S. 2005-0090801 A1, published Apr. 28, 2005) the disclosure ofwhich is incorporated by this reference in its entirety herein.Specifically, the flexible spinal needle may be used for CSA whileessentially eliminating the risk of PDPH.

BRIEF SUMMARY OF THE INVENTION

In order to improve the performance of a flexible needle, a flow elementis provided for use therewith. A flow element may be used with flexibleneedles, including flexible spinal needles, and flexible needleassemblies to prevent or at least minimize the extent to which flowocclusion may occur within a flexible needle, particularly when usedwith a flexible needle for minimizing incidence of post-dural punctureheadache. The flow element includes a body having an internal flow pathfor conducting a fluid through a flexible needle, and ananti-restriction member. The anti-restriction member includes anelongated body, a proximal end coupled to the body within the internalflow path, and a distal end for disposing at least a portion of theelongated body within a flexible needle.

In certain embodiments, a parallel flexible spinal needle assembly forminimizing flow occlusion through an internal flow path of a flexibleneedle by unintended kinking potentially caused by ligament or musclelayer movements is also provided.

In certain embodiments, a flexible spinal needle assembly, a flexiblespinal needle assembly kit, a method for installing a flexible spinalneedle assembly, and a process for producing a flow element areprovided.

Other advantages of the flexible needle and flexible needle assembly arenow described, in which a flow element may be used to advantage. Incontrast to a conventional spinal catheter, the instant flexible needleflow element is advantageously used with a flexible needle that providesfor simple and straightforward needle insertion without either threadinga catheter through a needle or installing an adapter. The installationprocedure is similar to intravenous catheter or “single-shot” spinalprocedures already familiar to clinicians. Placement of the flexibleneedle over the inserting needle allows a larger diameter flexibleneedle to be inserted. The resulting improved diameter flexible needleallows easier and faster flow of either cerebrospinal fluid (“CSF”) ormedicating agents.

Insertion of the flexible needle tip in the intrathecal space with theinstant device is more secure. The Pencil Point style non-cutting tip ofthe support needle promotes a low incidence of PDPH. However, theassembly tip may be shaped to provide a feedback signal when the dura ispunctured. Observation of CSF with the instant design further assures aclinician that the entire orifice at the flexible needle tip is in theintrathecal space.

The chance of neurologic damage is lessened with the shorter flexibleneedle. The shorter length is less likely to be wedged against a nerveroot. More importantly, the larger bore of the improved flexible needlepromotes turbulent flow and improved mixing of any injected fluid willoccur with CSF. The improved short flexible needle, which is inserted tothe hub, removes ambiguity about how far to insert it. The flexibleneedle hub greatly aids fixation to the skin. Contamination duringinsertion is less likely. Also, kinking at the skin is essentiallyimpossible when a flexible kink sleeve is included.

The relative ease, simplicity, and safety of the improved device mayexpand the use of continuous spinal anesthesia/analgesia. Lumbarepidurals could be replaced with this apparatus. Similarly, mostsingle-shot spinals may be replaced with this apparatus “just-in-case”the procedure goes longer than expected, or the level of the block needsadjustment. A number of situations outside the operating environmentcould benefit from this device, non-exclusively including: acute andchronic pain control with spinal narcotics, labor analgesia, diagnostictaps, and indwelling catheters for continuous peripheral nerve blocks aswell as research purposes. In effect, this apparatus may be used inmedical procedures involving needle insertion at the lumbar level of thespine. Versions of the instant device are contemplated to offer improvedtechniques for the insertion of a wide variety of medical catheters,including arterial lines, major nerve blocks, intraperitoneal catheters,intraventricular (brain) catheters, and intravenous catheters.

The instant device provides an apparatus and method for inserting aflexible spinal needle in a quick, easy, and straightforward manner.Such a flexible spinal needle assembly has an outside diameter sized sothat withdrawal of the assembly from the subarachnoid space, subsequentto insertion of the assembly thereby, permits the dura matersubstantially to reseal a space formerly occupied by the assembly. Anassembly typically includes a support needle, a flexible needle slidablymounted on the support needle, and a central stylet slidably insertedwithin the support needle. The inserted tip end of a flexible needleassembly is advantageously configured to produce a feedback signal toindicate dural puncture.

A support needle may have a piercing point on a first end and a centralhub at a second end. The piercing point protrudes from a front, distal,inserted, or tip, end of a flexible spinal needle assembly. A piercingpoint penetrates substantially without cutting, and helps to form apuncture hole through dura mater which automatically may substantiallyreseal subsequent to retraction of a flexible needle. A second end ofthe central stylet generally may have a locking hub. The locking hub maycarry a first attach structure to connect with corresponding structureof a central stylet.

The front end of the support needle may be configured cooperatively toform a structural interference with a distal end of a flexible needle.Such structural interference resists relative motion between thepiercing point and the distal end of the flexible needle duringinsertion of the flexible needle into a patient. A rear end of thesupport needle may carry a support hub having second attach structure toremovably connect to the central hub of the central stylet. The firstand second attach structures may be structured to form a removableconnection, such as a LUER-LOCK.™ type connection. The support hub maybe advantageously made from a transparent material to permit observationof fluid flow therethrough.

A flexible needle may be characterized as a flexible conduit havingdistal and proximal ends. Preferred flexible needles have sufficienttransverse flexibility to accommodate patient torso bending movement,thus operating to reduce a patient's awareness of the presence of thedevice. Flexible needles typically are made from medical grade plasticmaterials. For example, polyester shrink tube or similar materials maybe used. The distal end of a flexible needle may be reinforced, in someinstances, to resist peel-back from the front end of a support needle.

The transition from the proximal flexible needle hub to the flexibleneedle body may be reinforced by a kink sleeve segment. The kink sleevesegment may be constructed of a firm yet flexible material, such asnylon or other polymers. The kink sleeve is intended to cushion thetransition from the hub to the flexible needle body during bending thatwill occur after the flexible needle is inserted and the support needleremoved. For example, once the flexible needle is inserted, the hub maybe bent over and taped to the skin, often at an angle of around 90degrees.

Needle hubs are typically configured for fluid flow attachment tomedical fluid transfer equipment. For example, needle hubs may beconfigured to form LUER-LOCK.™ type connections with such equipment. Itmay be further preferred to form the needle hub for substantiallyunobtrusive attachment to a patient's skin by way of an intermediaryadhesive element or by designing the hub to lay flush against thepatient's skin with a connection parallel thereto without a need forbending the flexible needle.

A flexible needle assembly may be installed using a method similar tothe following: providing a flexible needle assembly as disclosed herein;using conventional spinal needle technique to prepare the skin of apatient at an injection site, apply local anesthetic, pierce skin andsubcutaneous fascia, and insert a piercing point tip of the flexiblespinal needle assembly; removing the central stylet subsequent toreceiving a feedback signal that puncture of the dura mater hasoccurred; checking for CSF at the support hub; if no CSF is observed,further inserting the assembly until the tip is within the intrathecalspace; or if CSF is observed, unlocking the support hub and the flexibleneedle hub, and while holding the support needle stationary, advancingthe flexible needle until the flexible needle hub contacts the skin;removing the support needle and checking for the presence of CSF at theflexible needle hub; disposing and connecting a flow element into aninternal flow path of the flexible needle to substantially reduce flowocclusion through the internal flow path caused by kinking; connectingmedical fluid transfer apparatus to an attachment hub of the flowelement; and finally, securing the flexible needle hub to the skin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded plan assembly view of a flexible needle assembly.

FIG. 2 is an exploded plan assembly view of a flexible needle assembly.

FIG. 3 shows a partial cross-sectional view of a flexible needle shownin FIG. 1.

FIG. 4 shows a detail view of a distal end portion of the flexibleneedle assembly tip shown in FIG. 1 when assembled.

FIG. 5 is a plan view of a flow element of the flexible needle assemblyshown in FIG. 2.

FIG. 6 shows an exploded view the flow element as indicated by referencein FIG. 5.

FIG. 7 shows a cross-sectional view taken along section line 7-7 in FIG.5.

FIG. 8 is a side assembled view of the flexible needle assembly shown inFIG. 2.

FIG. 9 representatively shows a portion of the flexible needle assemblyshow in FIG. 8 being kinked in ligament layers.

FIG. 10 shows a cross-sectional view of the flexible needle assemblytaken along section line 10-10 in FIG. 9.

FIG. 11 illustrates a cross-sectional view of a conventional flexibleneedle being partially occluded when bent in ligament layers.

FIG. 12 illustrates a cross-sectional view of a conventional flexibleneedle being fully occluded when kinked in ligament layers.

FIG. 13 shows a cross-sectional view of another flexible needleassembly.

FIG. 14 shows a cross-sectional view of a further flexible needleassembly.

FIG. 15 shows a cross-sectional view of yet another flexible needleassembly.

FIG. 16 shows a cross-sectional view of a flow element.

FIG. 17 shows a cross-sectional view of a flow element.

FIG. 18 shows a cross-sectional view of a flow element.

FIG. 19 is a side view of a flexible spinal needle assembly.

DETAILED DESCRIPTION OF THE INVENTION

The illustrations presented herein are, in some instances, not actualviews of any particular flow element, flexible needle assembly or otherfeature of a flexible spinal needle assembly, but are merely idealizedrepresentation that are employed to describe the invention.Additionally, elements common between figures may retain the samenumerical designation.

Generally, the flow element may be advantageously used with anintegrated spinal needle or flexible needle assembly 10 (much like anintravenous needle and catheter mounted therein) as shown in FIG. 1,however, in which the flexible needle 15 is releasably mounted on theoutside of a support needle 19. The flexible needle 15 is configured foruses with embodiments of the invention as will be further describedbelow, and is also configured for placement on the outside of thesupport needle 19 that provides a number of advantages which are firstdescribed before turning to the embodiments of the invention. First,this design makes insertion significantly easier by eliminating theseparate steps of catheter threading, insertion and hub/adapterattachment. A single “stick” is all that is required; once the needle isin, so is the flexible conduit for infusion of fluid therein. Since theflexible needle 15 is larger for a given needle size, its flow andhandling characteristics will be much improved, and it is easier andcheaper to manufacture. Advantageously, embodiments of the inventionprovide for a flow element 50 that may be introduced into the flexibleneedle 15 to minimize the effects of kinking by substantially preventingtotal flow occlusion of fluid therethrough and ensuring a minimal amountof fluid flow therein as shown in FIG. 2.

Shown in FIG. 1 is an exploded plan assembly view of a flexible needleassembly 10 usable in accordance with an embodiment of the invention.The flexible needle assembly 10 which is configured for use withembodiments of the invention consists of three components: a centralstylet 17, a hollow support needle 19, and a flexible needle 15. Theoverall dimensions of the flexible needle 15 and representatively theflexible needle assembly are generally represented in length, and may besimilar to a conventional spinal needle in gauge size ranging from about22 gauge to about 25 gauge in size, but as illustrated the flexibleneedle 15 is shown as being about 23 gauge cannula in size.

The innermost component of the assembly is configured as a solid centralstylet 17. When inserted in the support needle 19 (discussed in detailfurther herein), the central stylet 17 prevents the entry of extraneoustissue or other material into the support needle opening 28 duringinsertion. The central stylet may also serve as a “stiffening” portionof the assembly providing extra support and stiffness to the entireassembly. The hub 25 of the central stylet 17 is outermost, or locatedat an extreme proximal end 26 of assembly 10, because the central stylet17 is the first to be removed. An attachment structure, such as tab 32,may be located on the hub 25 for retaining the central stylet 17 in thesupport needle 19. The tab 32 may interact with a correspondingattachment structure on the hub 35 of the support needle 19.

The next layer of the assembly is a removable hollow support needle 19to support and allow insertion of the flexible needle 15 into a subject.This support needle 19 closely resembles a conventional spinal needle.The tip 27 of support needle 19 may have a pencil-point formation toallow penetration of tissue substantially without cutting. As discussedpreviously herein, this aids in forming a puncture hole through the duramater which automatically may substantially reseal subsequent toretraction. An opening 28 is located near the tip 27 to allow cerebralspinal fluid “CSF” or other fluids to flow through the support needle 19from the opening 28 to the hub 35. It will be appreciated that wheredesired, suitable treatment solutions may be injected through thesupport needle 19, to enter a patient's tissue through the opening 28.

The hub 35 of the support needle 19 may beneficially be made of clearplastic to allow visualization of CSF return when the central stylet 17has been removed, Of course, any CSF present will visibly flow from thedistal end 33 of support needle 19 subsequent to removal of the centralstylet 17. Optional use of clear plastic or a transparent fluidobservation window in the support hub 35 can provide an additionalconvenience, and minimize loss of CSF.

The central stylet 17 may be attachable to the support needle 19, asillustrated in FIG. 1. The central hub 25 typically carries an attachstructure, such as tab 32, to interface in a structural interferencewith an attach structure 34 carried by support hub 35. As illustrated,tab 32 and attach structure 34 cooperatively form a slidably engageablejoint. Alternative releasable retaining joint configurations, includingrotatable attachments such as LUER-LOCK.™ typejoints, may also be used.

The outermost layer of the assembly 10 is the flexible needle 15 itself.As previously described is approximately 23 gauge in size and about thelength of a conventional spinal needle, although different diameters andlengths for use with different procedures is within the scope of theinvention. Conventional plastic catheter material may be used in itsconstruction. The flexible needle material may be reinforced with a flatribbon internal spring 45 (shown in FIG. 4), an internal or externalwire wrap, or other reinforcing structure. Alternative materials, andvarious materials in combination, also may be used to construct aflexible needle 15. Suitable flexible needle material produces aflexible needle 15 which is fairly stiff and has a sufficiently hightensile strength to maintain structural integrity during insertion,while in the body, and during retraction from a patient. A flexibleneedle 15 desirably possesses sufficient transverse flexibility todeform and accommodate patient motion to reduce irritation from thepresence of a foreign body.

A slippery nonstick surface is generally provided to ease insertion andremoval of the flexible needle 15. The tip 29 of flexible needle 15 maybe tapered into a curve to blend smoothly into the edge of supportneedle 19 (see, FIGS. 4 & 19). The degree of this curved taper may begoverned by a tradeoff between the decreased resistance to insertion ofan extreme taper versus the fragility and tendency to peelback of a verythin leading edge. A preferred taper provides ease of insertion, afeedback signal to indicate entry of flexible needle 15 through thedura, and sufficient tensile strength to prevent peelback. The feedbacksignal may be described as a distinct “click” or a change in requiredinsertion force. The “click” may be a sonic event, or may be perceptibleonly through the clinician's fingers in contact with the assembly.

Flexible needle tips 29 having shapes in addition to those illustratedin FIGS. I and 4 are within contemplation. For example, manufacturing ormaterial requirements may influence the shape of a tip 29. Analternative flexible needle may include a reinforcing wire of finegauge. Such a wire may be embedded into the material forming the sealingwall of flexible needle 15 to reinforce against peelback. The wire mayalso be spiraled along the length of the flexible needle to provideadditional strength to resist collapse, kinking, or breakage of aflexible needle 15. Alternatively, a flat spring ribbon 45 may be usedto provide reinforcement.

The flexible needle hub 39 typically includes a LUER-LOCK.™ typeconnector, or other attachment structure, for easy and secure connectionwith common infusion tubing, injection ports, or syringes, and othermedical fluid transfer apparatus. Since the flexible needle 15 may beinserted all the way to the hub 39 a flat, circular flange, or otherergonomically shaped structure, may be provided on the surface of thehub which rests against the patient's skin to facilitate easy tapefixation. Fixation to the patient's skin may be accomplished with aslotted circular foam tape. Of course, other tapes or adhesive systemsma)y also be used. A quantity of suitable adhesive or tape could beincluded in a prepackaged flexible spinal needle assembly kit.

It is desirable to prevent inadvertent premature removal of the supportneedle 19 from the flexible needle 15. In the embodiment depicted inFIG. 1, support hub 35 receives thread structure 37 located on theflexible needle hub 39 and locks with rotation. Such a positiveconnection may be desirable and may form a LUER-LOCK.™ or otherrotatable-type joint. Other such interlocking or even alternativeretaining structure may also be used. For example, a secure friction fitattachment between support needle 19 and flexible needle 15 is withincontemplation in the practice of this invention, as is a structuralinterference fit of attachment structures similar to shown in connectionwith tab 32 on the central stylet 17.

As best shown in FIG. 3 showing a partial cross-sectional view of aflexible needle shown in FIG. 1, the flexible needle 15 may include aflexible kink sleeve 18. Kink sleeve 18 covers a portion of the proximalsurface of the flexible needle 15 to protect the area covered againstkinking and damage during bending. Desirably, the kink sleeve 18 willbegin at the base of the flexible needle 15 inside the hub 39 (asdepicted in FIG. 3) to provide maximum protection, although alternateembodiments where kink sleeve begins distal to the base of the flexibleneedle inside the hub 39, or at the base of the hub 39 are within thescope of the invention. Kink sleeve 18 may extend distally along thelength of the flexible needle I 5 to a length appropriate for theplanned use of the flexible needle. Typically, kink sleeve 18 willextend to a length sufficient to prevent kinking of the flexible needleat the skin of the patient or within the skin and fascia of the patient.Kink sleeve 18 may be constructed of any suitable flexible material thatis medically acceptable, including polymers such as nylon.

When flexible needle 15 is fully inserted, a portion of the kink sleeve18 may reside within the skin and fascia of the patient. The hub 39 maythen be bent over and taped to the skin, if desired. The kink sleeve 18acts to protect the flexible needle 15 during this bending process,which may bend the flexible needle 15 at an angle of about 90 degrees ormore. The kink sleeve 18 absorbs the force of the bend and maintains theflexible needle 15 in a position allowing flow therethrough. Kinking ofthe flexible needle 15 is thus minimized, and may be prevented. The kinksleeve 18 may be impregnated, coated, or otherwise treated with abiocompatible infection resistant substance to prevent adverse tissuereaction or infection at the flexible spinal needle entry site.

Flexible needles 15 may be made from suitable medical grade plastic typematerials. For example, polyester shrink tubing may be employed with oneembodiment of the device, although it will be appreciated that anysuitable material, including other polymers, may be used. Flexibleneedles 15 may be composed of a single material, or may be a compositeof two or more materials to provide the desired flexible needle handlingcharacteristics. Fine gauge wire, such as stainless steel wire, or aflat internal ribbon spring 45 (shown in FIG. 4), may be incorporatedinto a flexible needle sealable wall to improve resistance to peelbackand to further support the structural integrity of the flexible needle.The distal ends may alternatively be reinforced with metal bands. Hubs25, 35 and 39 are typically also made from medical grade plastic typematerials. The central stylet 17 and support needle 19 are typicallymade from a medically acceptable metal, such as stainless steel ortitanium.

The design of this device makes the placement of a spinal flexibleneedle 15 quick, easy, and straightforward. It should be so easy, infact, that most clinicians may choose to use this device for everyspinal procedure they perform. The initial steps of skin preparation,local anesthetic infiltration, and needle insertion are identical tothose now used with conventional spinal needles. As the flexible needleassembly 10 is being inserted and the clinician feels the slight “click”upon dural puncture, he or she removes the central stylet 17. If theinsertion has been successful, CSF will promptly appear at the hub 35 ofthe support needle 19. If the dura has not been penetrated, the entireassembly 10 may continue to be advanced until dural puncture isachieved. If desired, the central stylet 17 may be reinserted prior tocontinued advancement in order to prevent tissue from entering theopening 28.

Once CSF is observed at the hub 35 of the support needle 19, theclinician can be certain that the tip 29 of the flexible needle 15 iswithin the intrathecal space. If desirable for the procedure, theclinician may continue to advance the hollow support needle/flexibleneedle 19/15 of the assembly 10 another centimeter or so. At this point,the hub 35 of the hollow needle 19 is typically twisted to unlock itfrom the flexible needle hub 39, and while holding the hollow needle 19stationary, the flexible needle 15 is advanced all the way until the hub39 contacts the patient's skin. For embodiments including a kink sleeve18, this advancement may insert, or further insert, the kink sleeve 18within the patient's skin.

At this point, the hollow support needle 19 may be removed, and theappearance of CSF at the flexible needle hub 39 will confirm the correctplacement of the flexible needle 15. The desired injection port, tubing,or other medical fluid transfer apparatus, may then be attached to theflexible needle hub 39 such as by way of attach structure 37. Wherenecessary, the flexible needle 15 may be bent and taped to the patient'sskin before or after the attachment of the corresponding apparatus, ifrequired. Where included, kink sleeve 18 protects the flexible needle 15from kinking and damage at the bend. A piece of slotted, circular foamtape (which might also be treated with an antimicrobial) may also beapplied to fix the hub 39 to the skin, prevent dislodging of theflexible needle 15, and cushion the patient to reduce potentialirritation from the hub 39.

The flexible needle 15 may then be left in place for as long asclinically necessary and, assuming adequate tensile strength, be easilyand safely removed when appropriate. At the time of removal, since thenon-cutting point 22 of the support needle 19 substantially eliminatedlaceration of any fibers in the dural membrane, the mesh-like fibers mayrelax to their original position, thus automatically closing the duralpuncture. Therefore the PDPH incidence is expected to be in agreementwith Sprotte and Whitacre needles, despite the luxury of a reasonablylarge flexible needle 15 in a device usable to advantage with theinstant invention.

FIG. 2 is an exploded plan assembly view of a flexible needle assembly100 in accordance with a first embodiment of the invention. The flexibleneedle assembly 100 comprises a flexible needle 15 as previouslydescribed and a flow element 50, and may further comprise a centralstylet 17, and a hollow support needle 19. FIG. 8 shows a side assembledview of the flexible needle assembly 100 shown in FIG. 2. The overalldimensions of the flexible needle 15 and the flow element 50 aregenerally represented in length as indicated by reference line RI, andmay be similar to a conventional spinal needle in gauge size rangingfrom about 22 gauge to about 25 gauge in size, but as illustrated theflexible needle 15 is shown as being about 23 gauge cannula in size andthe flow element 50 being sufficiently small as to be disposed within aninner flow path 72 (shown in FIG. 8) of the flexible needle 15.

FIG. 5 is a plan view of the flow element 50 of the flexible needleassembly 100 shown in FIG. 2. The flow element 50 is advantageously usedwith the flexible needle 15 to further prevent kinking of the flexibleneedle 15 or from substantially occluding fluid flow therethrough wheninserted through muscle or ligament layers 90 of a subject asillustrated in FIG. 9. Illustratively, FIG. 10 shows a cross-sectionalview of the flexible needle assembly taken along section line 10-10 asshown in FIG. 9 where the flexible needle 15 is kinked and ananti-restriction member 56 of the flow element 50 prevents fluidocclusion within the inner flow path 72 thereof.

FIG. 11 illustrates a cross-sectional view of a conventional flexibleneedle 15 being partially occluded when bent in ligament layers and FIG.12 illustrates a cross-sectional view of a conventional flexible needle15 being fully occluded when kinked in ligament layers.

Returning to FIG. 5, The flow element 50 includes a body 52 having aninternal flow path 54 for conducting a fluid through the flexible needle15 and an anti-restriction member 56. The anti-restriction member 56includes an elongated bodies 58, a proximal end 60 coupled to the body52 within the internal flow path 54, and a distal end 62 for disposingat least a portion of the elogated body 58 within the flexible needle15. Advantageously, the elongated body 58 will help to maintain aminimal amount of fluid flow through the flexible needle 15 shouldkinking thereof occur. FIG. 9 representatively shows a portion of theflexible needle assembly 100 show in FIG. 8 being kinked in ligamentlayer 90 as mentioned above.

The body 52 may be made from any suitable material, and in thisembodiment is made from a medical grade plastic. The anti-restrictionmember 56 is made from a medical grade stainless steel and may be madefrom any other suitable material. The flow element 50 may bemanufactured by know methods, such as injection molding, by locating theanti-restriction member 56 into a mold and then forming the body 52about member 56. Other methods may be utilized to manufacture the flowelement 50, such as by forming the body 52 using conventional techniquesand then securing the anti-restriction member 56 to the body 52, forexample, with glue.

The body 52 may includes a cylindrical outer surface 53 extendingsubstantially between a first end 55 and a second end 57, wherein aportion of the cylindrical outer surface 53 is configured for sealingattachment to the attach structure 39 of the flexible needle 15. Aflexible conduit 64 may be coupled to the first end 55 of the body 52 tosupply fluid thereto or for connection to a machine configured fordelivering fluids thereto. A support hub 66 may be coupled to the body52, the support hub 66 having a first attach structure 68 configured toremovably attach to the attach structure 37 of the flexible needle toallow at least a portion of the elongated body 58 to be disposedtherein. Optionally, the first attach structure 68 may comprise aLUER-LOCK.™ type of connector or any other suitable connector type forattaching to the flexible needle 15.

FIG. 7 shows a cross-sectional view of the anti-restriction member 56taken along section line 7-7 in FIG. 5. As shown, the anti-restrictionmember 56 may includes two elongated bodies 58 in this embodiment. Alsoshown in FIG. 6, the two elongated bodies 58 comprise a twisted wirepair. Optionally, the twisted wire pair may be secured distally with aweld bead 70. Manufacturing the anti-restriction member 56 may includereceiving two wires and disposing them one on the other relative totheir axial lengths, optionally twisting them and further securing themwith a weld bead, such as to leave one end prepped for securing to, orforming with, the body 52 and the other end for disposing in a flexibleneedle as herein described. It is to be recognized that theanti-restriction member 56 may comprise one or three or more elongatedbodies other than the two elongated bodies 58 as illustrated by thetwisted wire pair. For example: FIG. 13 shows a flexible needle 15having a single elongated body 158 of an anti-restriction member 156disposed therein; FIG. 14 shows a flexible needle 15 having threeelongated bodies 258 of an anti-restriction member 256 disposed therein;and FIG. 15 shows a flexible needle 15 having four elongated bodies 358of an anti-restriction member 356 disposed therein, where eachembodiment provides a different amount of minimal fluid occlusion shouldthe flexible needle 15 be kinked when used.

It is to be recognized that each elongated body 58 of theanti-restriction member 56 while shown as a single uniform structure,may comprises two or more wires or elements banded, twisted or coupledtogether to form the unitary elongated body 58. However, in thisembodiment the anti-restriction member 56 comprises six wires (notshown) for each of the two elongated bodies 58 shown in FIG. 10.

Optionally, each elongated body 58 of the anti-restriction member 56 maybe configured with a cross-sectional shape of a circle as shown in FIG.10, an ellipse (not shown), diamond as shown in FIG. 17, a jack as shownin FIG. 16, a square (not shown), a triangle (not shown), a sigmoid asshown in FIG. 18 or any other suitable cross-sectional shape foradvantageously preventing and minimizing flow occlusion through aflexible spinal needle assembly 100.

Advantageously, the anti-restriction member 56 effectively maintains anopen channel within the inner flow path 72 of the flexible needle 15upon bending or kinking.

The flow element 50 may be designed where the distal end 62 of theelongated body 58 protrudes partially from a flexible distal end of theflexible needle 15 to allow the fluid to be dispersed more effectivelyfrom the cannula of the flexible needle 15, or may be designed in lengthto a greater or lesser extent than illustrated.

FIG. 19 is a perspective view of a flexible spinal needle 215. Theflexible spinal needle 215 may be used with a flow element 50 forminimizing flow occlusion through an internal flow path thereof byunintended kinking that is potentially caused by ligament or musclelayer movements when inserted into dura mater and into the intrathecalspace of a subject. The flexible spinal needle 215 includes an internalflow path (not shown) advantageously for receiving a flow element 50 forcoupling with the flexible needle 215 and disposed through a substantialportion of the internal flow path. The flexible needle includes anexterior diameter such that withdrawal of the flexible needle from thedura mater, subsequent to insertion of the flexible needle assemblytherethrough, permits the dura mater to substantially reseal a spaceformerly occupied by the flexible needle, and a tip and a flexibleneedle body of the flexible needle are of substantial elongated extentto be further extendable into the dura mater upon extraction of asupport needle coupled therewithin before exposing the flow element 50therewithin. Optionally, the distal end or tip 227 of the flexiblespinal needle 215 may include a curved portion 230 to facilitate furtherinsertion into an intrathecal space a subject upon removal of a supportneedle 19 that naturally strengthens while supporting the flexiblematerial characteristics of the flexible spinal needle 215. The curvedportion 230 may be manufactured by forming the material in the desiredshape or otherwise providing material strain or strain reliefstrategically located in a portion of the material forming the cannulaof the flexible spinal needle 215 the curved portion 230 may be formedusing manufacturing methods understood by a person of skill in the art.

In still other embodiments of the invention, a flexible spinal needleassembly kit is provided. The flexible spinal needle assembly kitincludes a flow element configured for minimizing flow occlusion througha flow path upon insertion into a flexible needle and a flexible needlehaving a flow path and configured for receiving a flow element or asupport needle within the flow path. The flexible spinal needle assemblykit may further include a support needle configured for insertion intothe flexible needle and to minimize the transverse flexibility of theflexible needle to enable insertion of the support needle and coaxiallysupported flexible needle through dura mater and into a spine of asubject. The flexible spinal needle assembly kit may also comprise acentral stylet configured for removable insertion into the supportneedle to prevent entry of matter through an opening proximate a distalend of the support needle when inserted into a subject.

Optionally, the flexible spinal needle assembly kit may include thesupport needle and the flexible needle pre-assembled allowing insertionof the pre-assembly into a patient facilitating removal of the supportneedle and subsequent insertion of the flow element into the flexibleneedle. Likewise, the central stylet, the support needle and theflexible needle may be pre-assembled for allowing insertion of thepre-assembly into a patient to facilitate removal of the support needleand central stylet and subsequent insertion of the flow element into theflexible needle.

A method for installing a flexible spinal needle assembly in accordancewith embodiments of the invention may include: inserting a distal end ofa flexible spinal needle assembly provided through dura mater and intoan intrathecal space of a subject, the spinal needle assemblycomprising: a support needle with a non-cutting piercing point at thedistal end and a hollow bore; a flexible needle with a tip at the distalend and slidably mounted on and supported by the support needle toexpose the piercing point slightly extending beyond the tip in thedistal end thereof, the flexible needle having an outside diametersufficiently small so that upon insertion of the flexible spinal needleassembly and withdrawal of the support needle from the flexible needlepermits the dura mater substantially to seal against the outsidediameter of the flexible needle; removing the support needle from withinthe flexible needle while maintaining the tip of the flexible needlewithin the intrathecal space to expose an inner flow path; andthereafter, connecting a flow element to the flexible needle disposingan anti-restriction member of the flow element into the inner flow pathof the flexible needle to substantially prevent fluid occlusion causedby bending or kinking of the flexible needle.

The method for installing a flexible spinal needle assembly may furtherinclude, prior to removing the support needle from within the flexibleneedle, verifying presence of cerebrospinal fluid in a proximal end ofthe flexible spinal needle assembly; if no cerebrospinal fluid isobserved, further inserting the distal end of the flexible spinal needleassembly through dura mater until the tip is at least in the intrathecalspace; and thereafter removing the support needle from within theflexible needle upon observing cerebrospinal fluid presence within theflexible spinal needle assembly.

Optionally, inserting the distal end of the flexible spinal needleassembly through dura mater and into the intrathecal space of thesubject comprises the outside diameter of the flexible needle beingsufficiently small so that upon withdrawal of the flexible needle fromdura mater, subsequent to insertion of the flexible spinal needleassembly therethrough, permits the dura mater substantially to reseal aspace formerly occupied by the flexible needle.

The method for installing a flexible spinal needle assembly may comprisea central stylet slidably mounted in the support needle to prevent theentry of matter through an opening in the distal end of the supportneedle during inserting, and further comprising prior to removing thesupport needle from within the flexible needle checking forcerebrospinal fluid at a proximate end of the spinal needle assembly; ifno cerebrospinal fluid is observed, replacing the central stylet andfurther inserting the spinal needle assembly until the tip is in theintrathecal space; and once cerebrospinal fluid is observed, thenremoving.

The method for installing a flexible spinal needle assembly may alsocomprise a central stylet slidably mounted in the support needle toprevent the entry of matter through an opening in the distal end of thesupport needle during inserting, and further comprising prior toremoving the support needle from within the flexible needle checking forcerebrospinal fluid at a proximate end of the spinal needle assembly; ifno cerebrospinal fluid is observed, replacing the central stylet andfurther inserting the spinal needle assembly until the tip is in theintrathecal space; and once cerebrospinal fluid is observed, thenremoving the support needle and the central stylet.

Optionally, removing the support needle from within the flexible needlecomprises advancing the flexible needle into the intrathecal space untila proximate end hub of the flexible needle contacts the subject.

The method for installing a flexible spinal needle assembly may furthercomprise subsequent to removing the support needle from within theflexible needle checking for the presence of cerebrospinal fluid at aflexible needle hub on a proximate end of the flexible needle prior todisposing the anti-restriction member of the flow element into the innerflow path of the flexible needle.

The method for installing a flexible spinal needle assembly mayoptionally comprise subsequent to removing the support needle fromwithin the flexible needle and after disposing the anti-restrictionmember of the flow element into the inner flow path of the flexibleneedle and connecting the flow element to the flexible needle connectingmedical fluid transfer apparatus to the flow element for supply fluidinto the inner flow path; and securing the flexible needle hub to thesubject.

The method for installing a flexible spinal needle assembly may stillfurther comprise prior to inserting the distal end of the flexiblespinal needle assembly through dura mater and into the intrathecal spaceof the subject, preparing the skin of a patient at an injection site;applying local anesthetic at the injection site; and inserting thedistal end of the flexible spinal needle assembly through the preparedinjection site.

The method for installing a flexible spinal needle assembly maycomprises checking for cerebrospinal fluid comprises removing thecentral stylet subsequent to receiving a feedback signal that punctureof the dura mater has occurred.

Lastly, the method for installing a flexible spinal needle assembly maycomprises a flow element comprising: a body having an internal flow pathfor conducting a fluid through the flexible needle; and theanti-restriction member having an elongated body, a proximal end coupledto the body within the internal flow path, and a distal end tofacilitate disposing at least a portion of the elongated body within theinner flow path of the flexible needle.

After having been apprised of the disclosure hereof, one of ordinaryskill in the art would be able to make and use the invention.

1. A flow element for use with flexible needles, the flow elementcomprising: a body having an internal flow path for conducting a fluidthrough a flexible needle; and an anti-restriction member having anelongated body, a proximal end coupled to the body within the internalflow path, and a distal end for disposing at least a portion of theelongated body within a flexible needle.
 2. The flow element of claim 1,wherein the body is made from a medical grade plastic, theanti-restriction member is made from a medical grade stainless steel andthe body includes a cylindrical outer surface extending substantiallybetween a first end and a second end, wherein a portion of thecylindrical outer surface is configured for sealing attachment to anattachment structure of a flexible needle.
 3. The flow element of claim2, further comprising a conduit coupled to the first end of the body anda support hub coupled to the body, the support hub having a first attachstructure configured to removably attach to an attach structure of aflexible needle while disposing at least a portion of the elongated bodytherein, the first attach structure comprises a lure lock typeconnector.
 4. The flow element of claim 1, wherein the elongated body ofthe anti-restriction member comprises two or more wires.
 5. The flowelement of claim 4, wherein the elongated body of the anti-restrictionmember comprises six wires.
 6. The flow element of claim 1, wherein theanti-restriction member comprises a plurality of elongated bodies. 7.The flow element of claim 6, wherein the plurality of elongated bodiescomprises a twisted wire pair, and each elongated body of the twistedwire pair comprises a plurality of wires.
 8. The flow element of claim6, wherein the plurality of elongated bodies are secured distally with aweld bead.
 9. The flow element of claim 1, further comprising a flexibleneedle removably attached to the body disposing at least a portion ofthe elongated body of the anti-restriction member within an inner boreof the flexible needle for preventing total occlusion of the internalflow path resulting from kinking of the flexible needle caused byligament or muscle layer movement in a subject.
 10. The flow element ofclaim 9, wherein the distal end of the elongated body protrudes from aflexible distal end of the flexible needle, the flexible needle isconfigured having an outside diameter sized so that withdrawal of theflexible needle from dura mater of a spine, subsequent to insertion of aflexible needle assembly through the dura mater, permits the dura matersubstantially to reseal a space formerly occupied by the flexibleneedle, the elongated body of the anti-restriction member is configuredfor substantially preventing partial occlusion of the internal flowpath, and the flexible needle is configured for slidably mounted on aportion of a support needle such that a first end of the support needleprotrudes from the flexible needle exposing a non-cutting piercing pointfor allowing the flexible needle and support needle to be insertedthrough the dura mater and into the intrathecal space of a subject andupon removal of the support needle is configured for disposing a portionof the anti-restriction member within the flexible needle.
 11. The flowelement of claim 10, wherein a flexible needle body of the flexibleneedle is of such substantial axial extent to be further extendable intothe dura mater upon extraction of a support needle, and the bodycomprises a support hub having a first attach structure, and a proximalend of the flexible needle carries a flexible needle hub having a secondattach structure configured to removably attach to the first attachstructure carried by the support hub.
 12. The flow element of claim 11,wherein the flexible needle comprises a cannula formed from a firstmaterial and radially reinforced over an extent toward a distal portionof the inner bore by a second material comprising a stainless steelribbon spring and further comprises a kink sleeve disposed on a portionof a flexible needle hub and over a portion of a cannula of the flexibleneedle.
 13. A flexible spinal needle assembly for minimizing flowocclusion through an internal flow path of a flexible needle byunintended kinking potentially caused by ligament or muscle layermovements, when inserted into dura mater and into the intrathecal spaceof a subject, the flexible spinal needle assembly comprising: theflexible needle having the internal flow path; and a flow elementcoupled to the flexible needle and disposed through a substantialportion of the internal flow path.
 14. The flexible spinal needleassembly of claim 13, wherein the flexible needle has an exteriordiameter such that withdrawal of the flexible needle from the duramater, subsequent to insertion of the flexible needle assemblytherethrough, permits the dura mater substantially to reseal a spaceformerly occupied by the flexible needle, and a tip and a flexibleneedle body of the flexible needle are of substantial elongated extentto be further extendable into the dura mater upon extraction of asupport needle coupled therewithin before exposing the flow elementtherewithin, and wherein the flow element is configured for attachmentto medical fluid transfer equipment having structure to form a luer locktype connection.
 15. The flexible spinal needle assembly of claim 13,wherein the flow element comprises: a body comprising the internal flowpath; and a member having a plurality of elongated bodies, a proximalend coupled to the body within the internal flow path, and a distal endfor disposing at least a portion of the plurality of elongated bodieswithin the flexible needle.
 16. The flexible spinal needle assembly ofclaim 13, wherein: the flexible needle has a flexible needle bodycomprising an elongated hollow tube and a flow path; and the flowelement is disposed in the flow path and configured for minimizing flowocclusion through the flow path.
 17. The flexible spinal needle assemblyof claim 16, comprising a flexible spinal needle assembly kit comprisinga prepackaged and sterilized assembly comprising the flow element andthe flexible needle.
 18. The flexible spinal needle assembly kit ofclaim 17, further comprising a support needle configured for insertioninto the flexible needle and to minimize the transverse flexibility ofthe flexible needle to enable insertion of the support needle andcoaxially supported flexible needle through dura mater and into a spinof a subject, and a central stylet configured for removable insertioninto the support needle to prevent entry of matter through an openingproximate a distal end of the support needle when inserted into asubject, wherein the support needle and the flexible needle arepre-assembled allowing insertion of the pre-assembly into a patientfacilitating removal of the support needle and subsequent insertion ofthe flow element into the flexible needle; wherein the flow element foruse with flexible needles comprises, a body having an internal flow pathfor conducting a fluid through a flexible needle; and ananti-restriction member having an elongated body, a proximal end coupledto the body within the internal flow path, and a distal end fordisposing at least a portion of the elongated body within a flexibleneedle.
 19. A method for installing a flexible spinal needle assembly,the method comprising: inserting a distal end of a flexible spinalneedle assembly provided through dura mater and into an intrathecalspace of a subject, the spinal needle assembly comprising: a supportneedle with a non-cutting piercing point at the distal end and a hollowbore; a flexible needle with a tip at the distal end and slidablymounted on and supported by the support needle to expose the piercingpoint slightly extending beyond the tip in the distal end thereof, theflexible needle having an outside diameter sufficiently small so thatupon insertion of the flexible spinal needle assembly and withdrawal ofthe support needle from the flexible needle permits the dura matersubstantially to seal against the outside diameter of the flexibleneedle; removing the support needle from within the flexible needlewhile maintaining the tip of the flexible needle within the intrathecalspace to expose an inner flow path; and thereafter, connecting a flowelement to the flexible needle disposing an anti-restriction member ofthe flow element into the inner flow path of the flexible needle tosubstantially prevent fluid occlusion caused by bending or kinking ofthe flexible needle.
 20. The method of claim 19, further comprising,prior to removing the support needle from within the flexible needle,verifying presence of cerebrospinal fluid in a proximal end of theflexible spinal needle assembly; if no cerebrospinal fluid is observed,further inserting the distal end of the flexible spinal needle assemblythrough dura mater until the tip is at least in the intrathecal space;and thereafter removing the support needle from within the flexibleneedle upon observing cerebrospinal fluid presence within the flexiblespinal needle assembly, wherein inserting the distal end of the flexiblespinal needle assembly through dura mater and into the intrathecal spaceof the subject comprises the outside diameter of the flexible needlebeing sufficiently small so that upon withdrawal of the flexible needlefrom dura mater, subsequent to insertion of the flexible spinal needleassembly therethrough, permits the dura mater substantially to reseal aspace formerly occupied by the flexible needle, and the spinal needleassembly further comprises a central stylet slidably mounted in thesupport needle to prevent the entry of matter through an opening in thedistal end of the support needle during inserting, and furthercomprising prior to removing the support needle from within the flexibleneedle checking for cerebrospinal fluid at a proximate end of the spinalneedle assembly; if no cerebrospinal fluid is observed, replacing thecentral stylet and further inserting the spinal needle assembly untilthe tip is in the intrathecal space; and once cerebrospinal fluid isobserved, then removing.
 21. The method of claim 19, further comprisingsubsequent to removing the support needle from within the flexibleneedle checking for the presence of cerebrospinal fluid at a flexibleneedle hub on a proximate end of the flexible needle prior to disposingthe anti-restriction member of the flow element into the inner flow pathof the flexible needle.
 22. The method of claim 19, further comprisingprior to inserting the distal end of the flexible spinal needle assemblythrough dura mater and into the intrathecal space of the subject,preparing the skin of a patient at an injection site; applying localanesthetic at the injection site; and inserting the distal end of theflexible spinal needle assembly through the prepared injection site. 23.The method of claim 19, wherein the flow element comprising: a bodyhaving an internal flow path for conducting a fluid through the flexibleneedle; and the anti-restriction member having an elongated body, aproximal end coupled to the body within the internal flow path and adistal end to facilitate disposing at least a portion of the elongatedbody within the inner flow path of the flexible needle.
 24. A processfor producing a flow element comprising: forming an anti-restrictionmember having an elongated body, a proximal end and a distal end, theelongated body configured for disposing at least a portion thereof byway of the distal end within a flexible needle; and securing theproximal end of the anti-restriction member to a body having an internalflow path for conducting a fluid through a flexible needle.
 25. Theprocess for producing a flow element of claim 24, wherein securing theproximal end of the anti-restriction member to the body comprisesinjection molding the body about the proximal end of theanti-restriction member, and forming the anti-restriction member havingthe elongated body comprises forming the anti-restriction member havingplurality of elongated bodies, at least one elongated body comprising aplurality of wires.